IOS can't change facebook AdChoices position by admob mediation

load native ad code:

        let adViewOptions = GADNativeAdViewAdOptions()
        adViewOptions.preferredAdChoicesPosition = .bottomRightCorner
        adLoader = GADAdLoader(adUnitID: unitId!,
                                   rootViewController: self.rootViewController,
                                   adTypes: [ .native],
                                   options: [ adViewOptions])
        adLoader.delegate = self
        let request = GADRequest()
        adLoader.load(request)

but i get Facebook adChoices on topRightCorner.

the admob native ad's adChoices is correct by adViewOptions.preferredAdChoicesPosition.

How can I set the Facebook adChoices position.

By the way, Is that facebook native ad can't receive ad event (imp、click) by GADNativeAdDelegate?